Method and apparatus for retrieving units from a storage system

ABSTRACT

A storage system and a load handling device for lifting and moving containers stacked in the storage system are described. The storage system includes a plurality of rails arranged in a grid pattern above the stacks of containers. The grid pattern has a plurality of grid spaces and each stack is located within a footprint of a single grid space. The load handling device can move laterally on the rails above the stacks and includes a container receiving space located above the rails in use and a lifting device arranged to lift a container from a stack into the container receiving space. The load handling device also includes a mechanism for enabling lateral movement of the device in one of two transverse directions by enabling either a first or second set of wheels to selectively engage the first or second set of rails.

FIELD

The present invention relates to apparatus for retrieving units form astorage system. In particular, but not exclusively, the inventionrelates to robotic devices for handling storage containers or bins in astore comprising a grid of stacked units.

This application claims priority from UK Patent Application No.GB1604100.6 filed on 10th March 2016, the entire content of which ishereby incorporated by reference.

BACKGROUND

Some commercial and industrial activities require systems that enablethe storage and retrieval of a large number of different products. Oneknown system for the storage and retrieval of items in multiple productlines involves arranging storage bins or containers on rows of shelvesarranged in aisles. Each bin or container holds a plurality of productsof one product type. The aisles provide access between the rows ofshelves, so that the required products can be retrieved by operatives orrobots that circulate in the aisles. It will be appreciated, however,that the need to provide aisle space to access the products means thatthe storage density of such systems is relatively low. In other words,the amount of space actually used for the storage of products isrelatively small compared to the amount of space required for thestorage system as a whole.

In an alternative approach, which offers a significant improvement instorage density, containers are stacked on top of one another and thestacks are arranged in rows. The containers are accessed from above,removing the need for aisles between the rows and allowing morecontainers to be stored in a given space.

Methods of handling containers stacked in rows have been well known fordecades. In some such systems, for example as described in U.S. Pat. No.2,701,065, free-standing stacks of containers are arranged in rows inorder to reduce the storage volume associated with storing suchcontainers while still providing access to a specific container ifrequired. Access to a given container is made possible by providingrelatively complicated hoisting mechanisms which can be used to stackcontainers and to remove given containers from stacks. The cost of suchsystems are, however, impractical in many situations and they havemainly been commercialised for the storage and handling of largeshipping containers.

The concept of using freestanding stacks of containers and providing amechanism to retrieve and store specific containers has been developedfurther, for example as described in EP 0 767 113 B (Cimcorp). Cimcorpdiscloses a mechanism for removing a plurality of stacked containersusing a robotic load handler in the form of a rectangular tube which islowered around the stack of containers, and which is configured to beable to grip a container at any level in the stack. In this way, severalcontainers can be lifted at once from a stack. The movable tube can beused to move several containers from the top of one stack to the top ofanother stack, or to move containers from a stack to an externallocation and vice versa. Such systems can be particularly useful whereall of the containers in a single stack contain the same product (knownas a single-product stack). The load handler can be used to movecontainers between single-product stacks, for example to add a pluralityof containers containing a single type of product to the store, and topick up one or more containers from two or more single-product stacks tocreate a multi-product output stack. An example of this is the pickingof vegetable crates in a central warehouse to create a multi-productorder for delivery to retail stores.

In the system described in Cimcorp, the height of the tube has to be asleast as high as the height of the largest stack of containers, so thatthat the highest stack of containers can be extracted in a singleoperation. Accordingly, when used in an enclosed space such as awarehouse, the maximum height of the stacks is restricted by the need toaccommodate the tube of the load handler. Furthermore, the system is notwell adapted for the selection of a single container from amulti-product stack.

Online retail businesses selling multiple product lines, such as onlinegrocers and supermarkets, require systems that are able to store tens oreven hundreds of thousands of different product lines. The use ofsingle-product stacks in such cases can be impractical, since a verylarge floor area would be required to accommodate all of the stacksrequired. Furthermore, it can be desirable only to store smallquantities of some items, such as perishables or infrequently-orderedgoods, making single-product stacks an inefficient solution.

Accordingly, for some applications, the use of multi-product stacks, inwhich the containers making up each stack may hold different products,is favoured in order to maximise the storage density of the system. Thestored items must remain accessible reasonably quickly and easily, sothat a plurality of different items required to fulfil a customer ordercan be picked from the storage system in an efficient way, even if someof the items required are stored in a lower level of a stack, underneathseveral other containers.

International patent application WO 98/049075A (Autostore), the contentsof which are incorporated herein by reference, describes a system inwhich multi-product stacks of containers are arranged within a framestructure. A system of this type is illustrated schematically in FIGS. 1to 4 of the accompanying drawings.

As shown in FIGS. 1 and 2, stackable containers, known as bins 10, arestacked on top of one another to form stacks 12. The stacks 12 arearranged in a grid frame structure 14 in a warehousing or manufacturingenvironment. FIG. 1 is a schematic perspective view of the framestructure 14, and FIG. 2 is a top-down view showing a stack 12 of bins10 arranged within the frame structure 14. Each bin 10 typically holds aplurality of product items (not shown), and the product items within abin 10 may be identical, or may be of different product types dependingon the application.

The frame structure 14 comprises a plurality of upright members 16 thatsupport horizontal members 18, 20. A first set of parallel horizontalmembers 18 is arranged perpendicularly to a second set of parallelhorizontal members 20 to form a plurality of horizontal grid structuressupported by the upright members 16. The members 16, 18, 20 aretypically manufactured from metal. The bins 10 are stacked between themembers 16, 18, 20 of the frame structure 14, so that the framestructure 14 guards against horizontal movement of the stacks 12 of bins10, and guides vertical movement of the bins 10.

The top level of the frame structure 14 includes rails 22 arranged in agrid pattern across the top of the stacks 12. Referring additionally toFIGS. 3 and 4, the rails 22 support a plurality of robotic load handlingdevices 30. A first set 22 a of parallel rails 22 guide movement of theload handling devices 30 in a first direction (X) across the top of theframe structure 14, and a second set 22 b of parallel rails 22, arrangedperpendicular to the first set 22 a, guide movement of the load handlingdevices 30 in a second direction (Y), perpendicular to the firstdirection. In this way, the rails 22 allow movement of the load handlingdevices 30 laterally in two dimensions in the horizontal X-Y plane, sothat a load handling device 30 can be moved into position above any ofthe stacks 12.

The load handling devices 30 are further described in Norwegian patentnumber 317366, the contents of which are incorporated herein byreference. FIGS. 3(a) and 3(b) are schematic perspective views of a loadhandling device 30 from the rear and front, respectively, and FIG. 3(c)is a schematic front perspective view of a load handling device 30lifting a bin 10.

Each load handling device 30 comprises a vehicle 32 which is arranged totravel in the X and Y directions on the rails 22 of the frame structure14, above the stacks 12. A first set of wheels 34, consisting of a pairof wheels 34 on the front of the vehicle 32 and a pair of wheels 34 onthe back of the vehicle 32, is arranged to engage with two adjacentrails of the first set 22 a of rails 22. Similarly, a second set ofwheels 36, consisting of a pair of wheels 36 on each side of the vehicle32, is arranged to engage with two adjacent rails of the second set 22 bof rails 22. Each set of wheels 34, 36 can be lifted and lowered, sothat either the first set of wheels 34 or the second set of wheels 36 isengaged with the respective set of rails 22 a, 22 b at any one time.

When the first set of wheels 34 is engaged with the first set of rails22 a and the second set of wheels 36 is lifted clear from the rails 22,the wheels 34 can be driven, by way of a drive mechanism (not shown)housed in the vehicle 32, to move the load handling device 30 in the Xdirection. To move the load handling device 30 in the Y direction, thefirst set of wheels 34 is lifted clear of the rails 22, and the secondset of wheels 36 is lowered into engagement with the second set of rails22 a. The drive mechanism can then be used to drive the second set ofwheels 36 to achieve movement in the Y direction.

The load handling device 30 is equipped with a crane device 40. Thecrane device 40 comprises a cantilever arm 42 that extends laterallyfrom the top of the vehicle 32. A gripper plate 44 is suspended from thecantilever arm 42 by four cables 46. The cables 46 are connected to awinding mechanism (not shown) housed within the vehicle 32. The cables46 can be spooled in or out from the cantilever arm 42, so that theposition of the gripper plate 44 with respect to the vehicle 32 can beadjusted in the Z direction.

The gripper plate 44 is adapted to engage with the top of a bin 10. Forexample, the gripper plate 44 may include pins (not shown) that matewith corresponding holes (not shown) in the rim that forms the topsurface of the bin 10, and sliding clips (not shown) that are engageablewith the rim to grip the bin 10. The clips are driven to engage with thebin 10 by a suitable drive mechanism housed within the gripper plate 44,which is powered and controlled by signals carried through the cables 46themselves or through a separate control cable (not shown).

To remove a bin 10 from the top of a stack 12, the load handling device30 is moved as necessary in the X and Y directions so that the gripperplate 44 is positioned above the stack 12. The gripper plate 44 is thenlowered vertically in the Z direction to engage with the bin 10 on thetop of the stack 12, as shown in FIG. 3(c). The gripper plate 44 gripsthe bin 10, and is then pulled upwards on the cables 46, with the bin 10attached. At the top of its vertical travel, the bin 10 is accommodatedbeneath the cantilever arm 42 and is held above the level of the rails22. In this way, the load handling device 30 can be moved to a differentposition in the X-Y plane, carrying the bin 10 along with it, totransport the bin 10 to another location. The cables 46 are long enoughto allow the load handling device 30 to retrieve and place bins from anylevel of a stack 12, including the floor level. The vehicle 32 issufficiently heavy to counterbalance the weight of the bin 10 and toremain stable during the lifting process. The weight of the vehicle 32may be comprised in part of batteries that are used to power the drivemechanism for the wheels 34, 36.

As shown in FIG. 4, a plurality of identical load handling devices 30are provided, so that each load handling device 30 can operatesimultaneously to increase the throughput of the system. The systemillustrated in FIG. 4 includes two specific locations, known as ports24, at which bins 10 can be transferred into or out of the system. Anadditional conveyor system (not shown) is associated with each port 24,so that bins 10 transported to a port 24 by a load handling device 30can be transferred to another location by the conveyor system, forexample to a picking station (not shown). Similarly, bins 10 can bemoved by the conveyor system to a port 24 from an external location, forexample to a bin-filling station (not shown), and transported to a stack12 by the load handling devices 30 to replenish the stock in the system.

Each load handling device 30 can lift and move one bin 10 at a time. Ifit is necessary to retrieve a bin 10 (“target bin”) that is not locatedon the top of a stack 12, then the overlying bins 10 (“non-target bins”)must first be moved to allow access to the target bin 10.

Each of the load handling devices 30 is under the control of a centralcomputer. Each individual bin 10 in the system is tracked, so that theappropriate bins 10 can be retrieved, transported and replaced asnecessary.

The system described with reference to FIGS. 1 to 4 has many advantagesand is suitable for a wide range of storage and retrieval operations. Inparticular, it allows very dense storage of product, and it provides avery economical way of storing a huge range of different items in thebins 10, while allowing reasonably economical access to all of the bins10 when required for picking.

For high-volume systems in which speed of operation is critical, it isimportant to maximise the performance of each of the load handingdevices, in terms of speed of operation, battery life, reliability,lifting capacity, stability and so on. It may therefore be desirable toprovide load-handling devices that offer improved performance in one ormore of these areas.

It may also be desirable to increase the number of load handling devicesin use at any one time, to allow an increase in the speed with whichitems can be retrieved from the storage system. For example, theApplicant's co-pending International Patent Application No.PCT/GB2013/051215, the content of which is incorporated herein byreference, describes a storage system in which a plurality of each oftwo different types of load handling device are provided. One type ofload handling device is adapted to lift a plurality of bins from a stackin one operation, to allow a target bin in the stack to be accessed by asingle-bin load handling device of the second type. In such cases, itmay be desirable to reduce the size of the load handling devices inorder to minimise instances in which the optimum movement path for onedevice is hindered by the presence of other devices.

It is against this background that the present invention has beendevised.

SUMMARY

According to the invention there is provided a load-handling device forlifting and moving containers stacked in stacks in a storage system, thesystem comprising a plurality of rails or tracks arranged in gridpattern above the stacks of containers, the grid pattern comprising aplurality of grid spaces, each stack being located within a footprint ofonly a single grid space, the load handling device being configured tomove laterally on the rails or tracks above the stacks, the loadhandling device further comprising a lifting mechanism, the liftingmechanism comprising a gripper device, the gripper device beingconfigured to grip a container from above, characterised in that theload-handling device comprises a vehicle comprising a body having anupper portion and a lower portion the upper portion for housingcomponents such as power components, and/or control components, and/ordrive components and/or lifting components the lower portion arrangeddirectly beneath the upper portion, the lower portion comprising acavity for accommodating a container and a wheel assembly, the wheelassembly comprising a first set of wheels for engaging with a first setof rails or tracks to guide movement of the device in a first directionand a second set of wheels for engaging with a second set of rails ortracks to guide movement of the device in a second direction, whereinthe second direction is transverse to the first direction; and thelifting mechanism being configured to raise and lower the gripper devicerelative to the cavity, the lifting mechanism being located above thecavity, the wheel assembly further comprises a wheel positioningmechanism, the wheel positioning mechanism comprising means forselectively engaging either the first set of wheels with the first setof rails or tracks or the second set of wheels with the second set ofrails or tracks thereby enabling the load handling device to selectivelymove in either the first or second direction across the grid.

From one aspect, the present invention concerns load handling devicesfor use in storage systems comprising a grid frame containing aplurality of stacks of containers. The load handling devices arearranged above the stacks of containers and are capable of lifting acontainer from a stack and moving the container laterally to anotherlocation. Advantageously, each load handling device occupies only asingle grid space in the storage system.

A load handling device according to an embodiment of the inventionincludes a container-receiving space into which a container can belifted. The container-receiving space is arranged beneath a vehiclemodule, in which components such as power components, controlcomponents, drive components and lifting components are housed.

By arranging the bulky components of the load handling device above thecontainer-receiving space, the footprint of the load handling device isreduced compared to the cantilever designs shown in FIGS. 3(a) to 3(c)and described in NO317366, in which the bulky components are housed in avehicle module disposed to one side of the container-receiving space.Advantageously, the load handling device of the invention occupies thespace above only one stack of containers in the frame, in contrast tothe cantilever design shown in FIGS. 3(a) to 3(c) which occupies thespace above two stacks. This means that, by virtue of the invention, theefficiency of operation of the storage system can be improved, becausethe reduced footprint allows more load handling devices to beaccommodated and reduces the likelihood of one device obstructing theoptimum path of another.

The load handling device preferably includes a set of wheels forsupporting the load handling device above the stacks. For example,lateral movement of the load handling device may be guided by railsdisposed above the frame. The rails may be arranged in a grid pattern,allowing two-dimensional movement of the load handling device in thehorizontal plane. The wheels may engage with the rails. Two sets ofwheels may be provided, with one set being arranged to engage with afirst set of rails to guide movement of the second handling device in afirst direction, and another set being arranged to engage with a secondset of rails to guide movement of the second handling device in a seconddirection.

The wheels are arranged at the periphery of the container-receivingspace. In one aspect of the invention, the wheels may be driven by oneor more motors housed in the vehicle module and drive may be transferredfrom the motors in the vehicle module to the wheels by drive transfermeans disposed around the container-receiving space. For example, thedrive transfer means may comprise a suitable arrangement of pulleys anddrive belts.

One or both set of wheels may be configured to be raised and loweredwith respect to the other set of wheels. One or more wheel lift motorsor other wheel lift devices may be housed in the vehicle module for thispurpose.

The vehicle module may house a winch or crane device for lifting thecontainer into the container-receiving space. The crane device mayinclude one or more motors for lifting the container, and the or eachmotor of the crane device may be housed in the vehicle module.

The crane device may include a gripper device configured to grip acontainer from above. The gripper device may be suspended from cablesthat can be extended and retracted from the vehicle to move the gripperdevice vertically.

The load handling device is equipped with a lifting device arranged tolift a single container from the stack into the container-receivingspace. The lifting device may comprise a pair of lifting arms arrangedon either side of the container-receiving space, in which case thelifting device may comprise a gripper device mounted between the ends ofthe arms and arranged to grip a container from above.

The lifting device comprises rods or cables arranged to engage withvertical channels formed in the side walls of the containers. Thechannels may be accessed by apertures in a top face of each container.In such an arrangement, vertically-extending spaces in the storagesystem are not necessary.

The rods or cables may carry an anchor mechanism arranged to engagereleasably with a container. For example, the anchor mechanism maycomprise one or more laterally-extendable arms for engaging a surface ofthe container. The anchor mechanism may be operated remotely, forexample by a wire that extends through a tubular bore of the rod orcable.

The load handling device further comprises an upper part, a lower partincluding a container-receiving space, and winch means for lifting acontainer into the container-receiving space. The winch means comprisesa winch motor which is housed in the upper part, above thecontainer-receiving space. The lower part includes a wheel assembly tofacilitate lateral movement of the load handling device with respect tothe frame, and the upper part also includes at least one motor fordriving one or more wheels of the wheel assembly.

The lower part may comprise a frame structure for supporting the wheelsof the wheel assembly. The frame structure may be arranged around thecontainer-receiving space. For example, the container-receiving spacemay be bounded on four sides by the frame structure. One or moreelements of the frame structure may be moveable to raise and lower afirst set of the wheels with respect to a second set of the wheels,thereby to facilitate engagement of either the first set of wheels orthe second set of wheels with a first or a second set of rails ortracks, respectively. The moveable elements of the frame structure maybe driven by a motor housed in the upper part of the load handlingdevice.

The load-handling device of the invention is preferably a self-propelledrobot vehicle.

From another aspect, the invention resides in a storage systemcomprising a frame containing a plurality of stacks of containers, andone or more load handling devices as described above. Each load handlingdevice occupies a single grid space, corresponding to the area occupiedby only one stack of containers.

In another aspect, the invention comprises a storage system comprising aframe containing a plurality of stacks of containers, a first handlingdevice capable of lifting a plurality of containers from a stack in asingle operation, and a second handling device capable of lifting asingle container and moving the container laterally. The first andsecond handling devices are disposed above the frame and areindependently moveable to access different stacks. The second handlingdevice is of the type described above, and occupies a spacecorresponding to only one stack of containers.

In this aspect, the provision of a first handling device capable oflifting a plurality of containers from a stack in a single operationalong with a second handling device capable of lifting a singlecontainer and moving the container laterally provides an optimumsolution when seeking to retrieve a container which is located in themiddle or bottom of a stack. In such a case, only two lifting operationsneed be carried out to retrieve the target container, which greatlyincreases the speed and efficiency of the retrieval process compared toprior art arrangements in which only one container can be lifted at atime.

The storage system may further comprise one or more port locations atwhich containers can be removed from and/or added to the storage system.The load handling device of the invention may be capable of transportinga target container from a stack to a port location. The containers maycomprise open-topped bins. The containers may be arranged to interlockor engage with one another in the vertical direction when formed in astack.

In a typical application, multiple handling devices may be employed sothat multiple containers can be lifted and moved simultaneously. Thehandling devices may be of different types, and may be selected tobalance the cost and energy consumption of the system with the speed andflexibility of operation. One benefit of the present invention is that,because the load handling devices occupy the space above only one stack,the efficiency of a multiple-device system can be improved compared toprior art load handling device designs which occupy two or more stackspaces. The gain in efficiency may arise from being able to accommodatemore load handling devices in a given system, from optimising therouting of the device using the space gained by the reduced devicefootprints, or from a combination of these factors.

Preferred and/or optional features of each aspect of the invention maybe used, alone or in appropriate combination in the other aspects of theinvention also.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a frame structure for housinga plurality of stacks of bins in a known storage system;

FIG. 2 is a schematic plan view of part of the frame structure of FIG.1;

FIGS. 3(a) and 3(b) are schematic perspective views, from the rear andfront respectively, of a known load handling device for use with theframe structure of FIGS. 1 and 2, and FIG. 3(c) is a schematicperspective view of the known load handling device in use lifting a bin;and

FIG. 4 is a schematic perspective view of a known storage systemcomprising a plurality of load handling devices of the type shown inFIGS. 3(a), 3(b) and 3(c), installed on the frame structure of FIGS. 1and 2.

Embodiments of the present invention will now be described, by way ofexample only, with reference to the remainder of the accompanyingdrawings, in which like reference numerals are used for like features,and in which:

FIG. 5 is a schematic perspective view of a load handling deviceaccording to an embodiment of the invention;

FIG. 6 is a schematic perspective view of the load handling device ofFIG. 5, showing one possible system architecture of the device;

FIG. 7 is a schematic perspective cut away view of the load handlingdevice of FIGS. 5 and 6, the load handling device;

FIG. 8 is a schematic perspective view of a second embodiment of theinvention, the load handling device comprising four displacement motorseach motor acting on a set of wheels on one side of the load handlingdevice;

FIG. 9 is a schematic perspective view of a third embodiment of theinvention, the load handling device comprising 4 moveable sides eachside comprising displacement mechanisms driven by a motor located withinthe load handling device;

FIG. 10 is a schematic perspective view of a fourth embodiment of theinvention, the load handling device comprising two sets of wheels, eachset of wheels comprising 4 individually driven wheels, each wheelcomprising a mechanism for engaging or disengaging the wheel with thetracks;

FIGS. 11 to 13 a and 13 b show schematic perspective views of a fifthembodiment of the invention, the load handling device comprising foursides, each side comprising two wheels, each side being liftable andlowerable with respect to the other sides by a mechanical solenoid andpin system.

DETAILED DESCRIPTION

FIG. 5 shows a load handling device 100 according to an embodiment ofthe invention. The load handling device 100 comprises a vehicle 102equipped with a winch or crane mechanism to lift a storage container orbin 106, also known as a tote, from above. The crane mechanism includeswinch cables and a grabber plate. The grabber plate is configured togrip the top of the container 106 to lift it from a stack of containers106 in a storage system of the type shown in FIGS. 1 to 4. It will beappreciated that the ride height of the load handling device changeswhen the moving means 188 is activated.

Referring also to FIGS. 6 and 7, the vehicle 102 comprises an upper part112 and a lower part 114.

The lower part 114 is fitted with two sets of wheels 116, 118, which runon rails provided at the top of the frame of the storage system. Atleast one wheel of each set 116, 118 is driven to enable movement of thevehicle 102 in X- and Y-directions respectively along the rails. As willbe explained below, one set of wheels 116 can be moved vertically tolift the set of wheels 116 clear of the respective rails leaving theremaining set of wheels in contact with the rails, thereby allowing thevehicle 102 to change direction.

The wheels 116, 118 are arranged around the periphery of a cavity orrecess 120, known as a container-receiving recess, in the lower part114. The recess 120 is sized to accommodate the bin 106 when it islifted by the crane mechanism 104, as shown in FIG. 6(a). When in therecess 120, the bin 106 is lifted clear of the rails beneath, so thatthe vehicle 102 can move laterally to a different location. On reachingthe target location, for example another stack, an access point in thestorage system or a conveyor belt, the bin 106 can be lowered from therecess 120 (as shown in FIG. 6(b)) and released from the grabber plate110.

The upper part 112 of the vehicle 102 houses all of the significantbulky components of the load handling device, as shown in FIG. 6(c). Theupper part 112 houses the battery and associated electronics,controllers and communications devices, motors for driving the wheels116, 118, motors for driving the crane mechanism 104, and other sensorsand systems.

In this way, the footprint of the vehicle 102 is larger than the size ofa bin 106 only enough to accommodate the wheels 116, 118 either side ofthe recess 120. In other words, the vehicle 102 occupies a single gridspace in the storage system. In this way, the vehicle 102 thereforetakes up the minimum possible amount of space in the X-Y plane.

The load handling devices 100 of the invention can also offer improvedstability, as the mechanical components displacing the or each set ofwheels with respect to each other are located in the lower part 114 ofthe load handling device.

In the first embodiment of the invention as shown in FIGS. 5 to 7 thefirst set of wheels 116 can be raised clear of the rails or lowered ontothe rails by means of a wheel positioning mechanism. Each wheel 116 ismounted on an arm 180 that is pivotally mounted at its outer end. Aninner end of each arm 180 is connected to the lower end of a respectivelinkage 182. The upper ends of both linkages 182 are connected to thelower end of a common linkage 184. In turn, the upper end of the commonlinkage 184 is moved by a motor or solenoid or worm gear or lead screwmechanism or any suitable means for drawing the common linkage upwards.By operating the moving means 188 to draw the common linkage 184upwards, the first set of wheels 116 can be raised so that the secondset of wheels 118 alone is engaged with the rails, allowing movement ofthe vehicle 102 in the Y-direction. By operating the motor 188 to pushthe common linkage 184 downwards, the first set of wheels 116 movedownwards to engage with the rails and to lift the vehicle so that thesecond set of wheels 118 is lifted clear of the rails, as shown in Thevehicle 102 can then move in the X-direction.

The wheels 118 of the second set are mounted to fixed T-pieces 190disposed at either end of the lower part 114 of the vehicle 102.

In the embodiment shown in FIG. 7, it will be appreciated that twomotors 118 are required, one to move two of the wheels of the set 116 ofwheels and one to move the remaining two of the wheels of the set 116disposed on the opposite side of the load handling device. In this way,one displacement motor acts to lift half a set of wheels only. It willbe appreciated that the motors 188 may operate independently, each onelifting or lowering half a set of wheels at any time. However in orderto efficiently change direction the motors 188 operate independently butat the same time to lift the wheels clear of the tracks.

It will be appreciated that in this embodiment of the invention themechanism for displacing the wheels is disposed in the lower part of thevehicle body. In this way, additional weight is disposed lower down inthe vehicle body thereby improving the stability of the load handlingdevice.

FIG. 8 shows a second embodiment of the invention in which the wheelsdisposed on each side of the load handling device each comprise themechanism only associated with one set of wheels in the previousembodiment described with reference to FIGS. 5 to 7. In this embodimentit will be appreciated that each side of the load handling device willtherefore require a displacement motor and a linkage mechanism asdescribed with reference to FIGS. 5 to 7. It will be appreciated thatthis provides additional stability to the load handling device as eachside comprises the same mechanism and motor means, the weight beingevenly distributed. The embodiment of FIG. 8 shows a load handlingdevice in which 4 motor means are provided each acting on half a set ofwheels 116, 118.

FIG. 9 shows a third embodiment of the invention in which the two wheelsdisposed on each side of the load handling device are rotatably attachedto moveable side panels that comprise the sides of the load handlingdevice. Two wheels 200 mounted in a frame structure 210 of a loadhandling device according to another embodiment of the invention. As inthe previous embodiments, in this embodiment the load handling devicecomprises a vehicle with an upper part 112 that houses the majorcomponents of the device and a lower part having a recess 120 foraccommodating a bin, with the wheels 200 being arranged on four sides ofthe recess.

In this case, the frame structure of the load handling device comprisestwo parallel panels that accommodate the wheels 200 there between. Drivemeans is provided to transfer drive to the wheels 200 from a motorhoused in the upper part 112 of the vehicle. It will be appreciated thatthe drive means provided in the upper part of the load handling devicemay act on two wheels 200 on one side of the load handling device at anyone time. In this way, a single motor means located above the cavity mayact on half a set of wheels 116 or two motors may be provided each motoracting on half a set of wheels 116.

Referring additionally to FIG. 10, in a fourth embodiment of theinvention each wheel 200 may be provided with displacement means toenable each wheel 200 to be independently lifted or lowered and engagedor disengaged with the track as required. In this embodiment the wheels200 each comprise drive means and displacement means. Again, in usingmechanisms and components positioned in the lower part of the loadhandling device the stability of the device is improved.

Referring to FIGS. 11 to 13 a and 13 b, a fifth embodiment ofdisplacement means for the wheels 200 or sets of wheels 116 and 118 isdescribed. FIG. 11 shows a two wheels disposed on each side of the loadhandling device, attached to moveable side panels that comprise thesides of the load handling device. As can be seen in FIGS. 12, 13 a, and13 b, the panels further comprise a pin and track mechanism, the pinslocating in the tracks when the panels are in situ on the sides of theload handling devices.

The panels further comprise a motor or solenoid that moves the pinlaterally in the track, the shape of the track in the inside of thepanels and the movement of the pins in the tacks causing the side panelsto be displaced upwardly or downwardly depending on the direction oftravel of the pin in the track. This movement in the panel causing thewheels associated with each panel to lift off the track or engage thetrack accordingly.

In this way, the wheels 200 in this embodiment can be raised and loweredby moving the panels independently at the same time or opposing panelsbeing connected so as to move together, relative to the upper part 112of the vehicle. The panels are mounted to a body 230 of the upper part112 of the vehicle by way of rails 232. The rails 232 are fixed to thebody 230, and pin is slidably mounted to the rails 232.

Although in some of the Figures only one side of the load handlingdevice is shown, it will be appreciated that an identical structurewould be provided on the opposite side of the vehicle. Both structuresmay be raised and lowered by a common motor, so the four wheels 200 canbe lifted and lowered in unison to control engagement of this first setof wheels 200 with rails extending in a first direction across theframe. It will be appreciated that two opposing panels may be raised andlowered by a single motor, the other two opposing panels being raisedand lowered by a further motor. Furthermore, each of the four panels maybe provided with a motor to independently raise and lower each panel.

It will be appreciated that in all the embodiments described above, themotors may be replaced by solenoids or worm gears or lead screwmechanisms or belt driving systems or any other suitable means fordriving the displacement mechanism.

It will be appreciated that many different variations and modificationsare possible. For example, both sets of wheels may be powered by asingle motor, with a suitable transfer arrangement to direct power tothe appropriate set of wheels. Instead of a motor, the mechanism used tolift the wheels may use linear actuators, such as linear motors orhydraulic rams.

Other variations and modifications not explicitly described above willalso be apparent to the skilled reader.

EXEMPLARY FEATURES

Exemplary Feature 1 can include a load-handling device (100) for liftingand moving containers (106) stacked in stacks in a storage system, thesystem comprising a plurality of rails or tracks arranged in gridpattern above the stacks of containers, the grid pattern comprising aplurality of grid spaces, each stack being located within a footprint ofonly a single grid space, the load handling device being configured tomove laterally on the rails or tracks above the stacks, the loadhandling device further comprising a lifting mechanism (104), thelifting mechanism comprising a gripper device (110), the gripper device(110) being configured to grip a container (106) from above,characterised in that the load-handling device (100) comprises:

a vehicle (102) comprising a body having an upper portion (112) and alower portion (114):

the upper portion (112) for housing components such as power components,and/or control components, and/or drive components and/or liftingcomponents;

the lower portion (114) arranged directly beneath the upper portion(112), the lower portion (114) comprising a cavity (120) foraccommodating a container (106) and a wheel assembly, the wheel assemblycomprising a first set of wheels (116) for engaging with a first set ofrails or tracks to guide movement of the device in a first direction anda second set of wheels (118) for engaging with a second set of rails ortracks to guide movement of the device (100) in a second direction,wherein the second direction is transverse to the first direction; and

the lifting mechanism (104) being configured to raise and lower thegripper device (110) relative to the cavity (120), the lifting mechanism(104) being located above the cavity (120),

the wheel assembly further comprises a wheel positioning mechanism, thewheel positioning mechanism comprising means for selectively engagingeither the first set of wheels with the first set of rails or tracks orthe second set of wheels with the second set of rails or tracks therebyenabling the load handling device to selectively move in either thefirst or second direction across the grid.

Exemplary Feature 2 can include a load handling device (100) accordingto feature 1, wherein the wheel positioning mechanism further comprisesa member pivotally mounted at its outer end to each of the wheels, themechanism further comprising two linkages, the inner end of each armbeing connected to a linkage 182, the upper ends of both linkages 182being connected to the lower end of a common linkage 184.

Exemplary Feature 3 can include a load handling device according tofeature 2 in which the wheel positioning mechanism further comprisesmotor means acting on the common linkage 184, the motor acting so as todraw the common linkage 184 upwardly.

Exemplary Feature 4 can include a load handling device according tofeature 3 in which the motor means comprises a motor, or a solenoid, ora worm gear, or a lead screw mechanism.

Exemplary Feature 5 can include load handling device according tofeature 1 in which the wheel positioning mechanism comprises two motors188, a first motor to move two of the wheels of the set 116 of wheelsand a second motor to move the remaining two of the wheels of the set116 disposed on the opposite side of the load handling device such thatone motor acts to lift half a set of wheels only.

Exemplary Feature 6 can include a load handling device according tofeature 5 in which the motors 188 may operate independently, each motorbeing adapted so as to lift or lower half a set of wheels at any time.

Exemplary Feature 7 can include a load handling device according tofeature 6 in which the motors 188 each operate independently of theother and further comprise means for lifting the wheels clear of thetracks or rails.

Exemplary Feature 8 can include a load handling device according tofeature 1, the wheel positioning mechanism comprising movable sidepanels on each side of the load handling device, the wheels disposed oneach side of the load handling device being rotatably attached to themoveable side panels.

Exemplary Feature 9 can include a load handling device according tofeature 8, wherein the wheels 200 mounted on each side of the loadhandling device are mounted in a frame structure 210 of the loadhandling device.

Exemplary Feature 10 can include a load handling device (100) accordingto feature 9, wherein the frame structure (210) is arranged around thecavity (120).

Exemplary Feature 11 can include a load handling device (100) accordingto feature 9, wherein the cavity (120) is defined within the framestructure (210).

Exemplary Feature 12 can include a load handling device (100) accordingto features 10 or 11, wherein the cavity (120) is bounded on four sidesby the frame structure (210).

Exemplary Feature 13 can include a load handling device (100) accordingto any preceding features 1 to 12, wherein the wheel assembly comprisesone or more of the wheels driven by a motor integrated with the wheel orlocated adjacent to the wheel.

Exemplary Feature 14 can include a load handling device (100) accordingto any preceding features 1 to 13, wherein one or more of the wheelscomprises a wheel hub motor (256).

Exemplary Feature 15 can include a load handling device (100) accordingto any preceding features 1 to 14, wherein one or more of the wheels isdriven by one or more motors located above the cavity (120).

Exemplary Feature 16 can include a load handling device (100) accordingto feature 15, further comprising drive transfer means disposed aroundthe cavity (120) for transferring drive from the or each motor to the oreach wheel.

Exemplary Feature 16 can include a load handling device (100) accordingto feature 16, wherein the drive transfer means comprises an arrangementof pulleys and drive belts.

Exemplary Feature 18 can include a load handling device (100) accordingto any preceding features 1 to 17, wherein one or more of the wheelsincludes a channel that cooperates with a drive belt for driving thewheel.

Exemplary Feature 19 can include a load handling device according tofeature 1, the wheels disposed on each side of the load handling deviceare rotatably attached to moveable side panels that comprise the sidesof the load handling device, the movable side panels further comprisinga pin and track mechanism, the pins locating in the tracks when thepanels are in situ on the sides of the load handling devices.

Exemplary Feature 20 can include a load handling device according tofeature 19, the side panels further comprising a motor or solenoid thatmoves the pin laterally in the track, the shape of the track in theinside of the panels and the movement of the pins in the tacks causingthe side panels to be displaced upwardly or downwardly depending on thedirection of travel of the pin in the track such that movement in thepanel causes the wheels associated with each panel to lift off the trackor rails or engage the track or rails accordingly.

Exemplary Feature 21 can include a load handling device according tofeature 20 in which the side panels are mounted to a body 230 of anupper part 112 of the vehicle by way of rails 232, the rails 232 beingfixed to the body 230, and the pin being slidably mounted to the rails232.

Exemplary Feature 22 can include a storage system comprising at leastone of the load handling devices of any preceding features 1 to 21.

Exemplary Feature 23 can include a method of moving at least one loadhandling device according to any preceding features 1 to 21 around thetracks or rails above a storage system, comprising the step ofselectively engaging a first set of wheels with a first set of rails ortracks or a second set of wheels with a second set of rails or trackssuch that depending on the selection the load handling device moves in afirst or second direction.

What is claimed is:
 1. A load-handling device for lifting and movingcontainers stacked in stacks in a storage system, the system including aplurality of rails or tracks arranged in grid pattern above the stacksof containers, the grid pattern having a plurality of grid spaces, eachstack being located within a footprint of only a single grid space, theload handling device being configured to move laterally on the rails ortracks above the stacks of containers, the load handling comprising, theload-handling device comprising: a lifting mechanism, the liftingmechanism including a gripper device, the gripper device beingconfigured to grip a container from above; a vehicle having four sidesforming a body, said body having an upper portion and a lower portion:the upper portion for housing components such as power components,and/or control components, and/or drive components and/or liftingcomponents; and the lower portion arranged directly beneath the upperportion, the lower portion including a cavity bounded by the four sidesfor accommodating a container and a wheel assembly, the wheel assemblyhaving a first set of wheels for engaging with a first set of rails ortracks to guide movement of the device in a first direction and a secondset of wheels for engaging with a second set of rails or tracks to guidemovement of the device in a second direction, wherein the seconddirection is transverse to the first direction; wherein: the liftingmechanism is configured to raise and lower the gripper device relativeto the cavity, the lifting mechanism being located above the cavity, thewheel assembly further comprises a wheel positioning mechanism, thewheel positioning mechanism including means for selectively engagingeither the first set of wheels with the first set of rails or tracks orthe second set of wheels with the second set of rails or tracks therebyenabling the load handling device to selectively move in either thefirst or second direction across the grid, and the wheel positioningmechanism further including moveable side panels that comprise the sidesof the load handling device, the wheels disposed on each side of theload handling device being rotatably attached to the moveable sidepanels.
 2. The load handling device of claim 1, wherein opposing sidewalls are raised and lowered by a common motor so that the first orsecond sets of wheels are lifted and lowered in unison to controlengagement of the respective first or second sets of wheels with thefirst or second sets of rails.
 3. The load handling device of claim 1,wherein opposing side panels are raised and lowered by a single motorand the other two opposing side panels are and lowered by a furthermotor.
 4. The load handling device of claim 3, wherein each of themoveable side panels comprises a pin and track mechanism, the pinslocating in the tracks when the panels are on the sides of the loadhandling device.
 5. The load handling device of claim 4, wherein theshape of the track inside of the moveable side panels is such that themovement of the pins in the tracks causes the side panels to bedisplaced upwardly or downwardly depending on the direction of travel ofthe pin in the track.
 6. The load handling device of claim 4, whereineach of the panels comprise a motor or solenoid that moves the pinlaterally in the track.
 7. The load handling device of claim 5, whereineach of the panels comprise a motor or solenoid that moves the pinlaterally in the track.
 8. The load handling device of claim 1, whereineach of the moveable side panels comprises a pin and track mechanism,the pins locating in the tracks when the panels are on the sides of theload handling device.
 9. The load handling device of claim 8, whereinthe shape of the track inside of the moveable side panels is such thatthe movement of the pins in the tracks causes the side panels to bedisplaced upwardly or downwardly depending on the direction of travel ofthe pin in the track.
 10. The load handling device of claim 9, whereineach of the panels comprise a motor or solenoid that moves the pinlaterally in the track.
 11. The load handling device of claim 2, whereineach of the moveable side panels comprises a pin and track mechanism,the pins locating in the tracks when the panels are on the sides of theload handling device.
 12. The load handling device of claim 11, whereinthe shape of the track inside of the moveable side panels is such thatthe movement of the pins in the tracks causes the side panels to bedisplaced upwardly or downwardly depending on the direction of travel ofthe pin in the track.
 13. The load handling device of claim 12, whereineach of the panels comprise a motor or solenoid that moves the pinlaterally in the track.